WO2023140262A1

WO2023140262A1 - Copolymer, composition, varnish, and cured products of these

Info

Publication number: WO2023140262A1
Application number: PCT/JP2023/001239
Authority: WO
Inventors: 亨荒井
Original assignee: デンカ株式会社
Priority date: 2022-01-19
Filing date: 2023-01-17
Publication date: 2023-07-27
Also published as: TW202340269A; JPWO2023140262A1

Abstract

Provided is an aromatic vinyl compound-aromatic polyene copolymer that satisfies all of conditions (1) to (4). (1) The number average molecular weight of the copolymer is at least 500 and less than 100,000. (2) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8-20 carbon atoms, and the content of aromatic vinyl compound monomer units is more than 70 mass%. (3) The aromatic polyene is one or more types selected from among polyenes having 5-20 carbon atoms and having a plurality of vinyl groups and/or vinylene groups in the molecule, and the content of vinyl groups and/or vinylene groups derived from aromatic polyene units is at least 2 and less than 30, and preferably at least 3 and less than 30, per number average molecular weight. (4) The copolymer may contain one or more types selected from among olefin monomer units having 2-20 carbon atoms, and in a case where aromatic vinyl compound monomer units and aromatic polyene monomer units are present, the total amount of these and olefin monomer units is 100 mass%.

Description

Copolymers, compositions, varnishes, and cured products thereof

TECHNICAL FIELD The present invention relates to insulating materials that are copolymers, compositions, varnishes, and cured products thereof.

As the communication frequency shifts to the gigahertz band and higher frequency bands, there is an increasing need for multilayer substrates made of CCL or FCCL containing an insulating material with low dielectric properties. Fluorine-based resins such as perfluoroethylene are characterized by excellent low dielectric constant, low dielectric loss, and excellent heat resistance. On the other hand, substrates and insulating materials using post-curing resins such as epoxy resins, unsaturated polyester resins, polyimide resins, and phenolic resins have been widely used due to their heat resistance and ease of handling.

Therefore, attention is focused on hydrocarbon-based resins that inherently have low dielectric properties. In order to make a hydrocarbon resin, which is originally a thermoplastic resin, into a curable resin, it is necessary to introduce a functional group, but in general, the functional group that reacts to radicals or heat has polarity, which deteriorates the low dielectric properties. When trying to introduce a functional group composed only of a hydrocarbon, such as an aromatic vinyl group, in many cases, an intermolecular reaction between expensive hydrocarbon-based monomers is used (Patent Document 2), which is often uneconomical. Patent Document 3 discloses a cured product composed of an ethylene-olefin (aromatic vinyl compound)-aromatic polyene copolymer and a non-polar vinyl compound copolymer obtained from a specific coordination polymerization catalyst and having a specific composition and formulation. In the case of this technology, only one of the two vinyl groups of the aromatic polyene (divinylbenzene) is selectively copolymerized and the remaining vinyl groups are preserved, so that it is possible to easily obtain a crosslinkable hydrocarbon-based copolymer macromonomer having aromatic vinyl functional groups. A cured product obtained from a similar composition of an olefin-aromatic vinyl compound-aromatic polyene copolymer and a composition with an auxiliary material or the like is characterized by a low dielectric constant and a low dielectric loss tangent (Patent Documents 4 and 5).

The low dielectric properties of known hard crosslinkable raw materials are not sufficient, and there is a problem that the low dielectric properties of the cured product deteriorate when a large amount is blended. When a relatively large amount of inorganic filler is blended, the dielectric constant of the resulting cured product increases because inorganic fillers generally have a high dielectric constant. In addition, a low-dielectric and curable aromatic vinyl compound-aromatic polyene copolymer obtained by cationic polymerization is known (Patent Document 6), but the copolymer according to this prior art has a dendritic (tree-like) structure, so there are many polymer terminal structures, and because of the contained terminal structure peculiar to cationic polymerization, the molecular design for improving heat resistance and durability is complicated.

JP-A-6-192392 JP-A-2004-087639 Japanese Patent Application Laid-Open No. 2007-217706 WO2021/112087 WO2021/112088 WO2018/181842

The olefin-aromatic vinyl compound-aromatic polyene copolymers described in the above-mentioned published patent documents are relatively soft and exhibit good solubility in solvents such as toluene, ethylbenzene, and limonene.

In order to solve the above-described problems that the prior art could not solve, the present invention provides an aromatic vinyl compound-aromatic polyene copolymer that can give a harder cured product and has high solubility in solvents. Also provided is a harder cured product containing an aromatic vinyl compound-aromatic polyene copolymer.

The present invention can provide the following aspects.

Mode 1.
An aromatic vinyl compound-aromatic polyene copolymer that satisfies all of the following conditions (1) to (4).
(1) The copolymer has a number average molecular weight of 500 or more and less than 100,000.
(2) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and the content of the aromatic vinyl compound monomer units exceeds 70% by mass.
(3) The aromatic polyene is one or more selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and/or vinylene groups in the molecule, and the content of vinyl groups and/or vinylene groups derived from the aromatic polyene units is 2 or more and less than 30 per number average molecular weight.
(4) One or more selected from olefin monomer units having 2 to 20 carbon atoms may be included, and the sum of the aromatic vinyl compound monomer units and the aromatic polyene monomer units and, if present, the olefin monomer units is 100% by mass.

Mode 2.
The aromatic vinyl compound-aromatic polyene copolymer according to aspect 1, wherein the content of the olefin monomer unit is 0% by mass or more and less than 30% by mass with respect to the total 100% by mass of the aromatic vinyl compound monomer unit, the aromatic polyene monomer unit, and the olefin monomer unit when present.

Mode 3.
The aromatic vinyl compound-aromatic polyene copolymer according to aspect 2, which does not contain olefin monomer units.

Mode 4.
A composition comprising the aromatic vinyl compound-aromatic polyene copolymer according to any one of aspects 1 to 3 and one or more selected from the following (a) to (d).
(a) a curing agent (b) one or more resins selected from hydrocarbon elastomers, polyphenylene ether resins and aromatic polyene resins (c) monomers (d) another olefin-aromatic vinyl compound-aromatic polyene copolymer (i) that satisfies all of the following conditions (i) to (iv): the copolymer has a number average molecular weight of 500 or more and less than 100,000.
(ii) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and the content of aromatic vinyl compound monomer units is 70% by mass or less.
(iii) The aromatic polyene is one or more selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and/or vinylene groups in the molecule, and the content of vinyl groups and/or vinylene groups derived from the aromatic polyene units is 1.5 or more and less than 20 per number average molecular weight.
(iv) The olefin is one or more selected from olefins having 2 to 20 carbon atoms, the content of olefin monomer units is 30% by mass or more, and the total of the olefin monomer units, aromatic vinyl compound monomer units and aromatic polyene monomer units is 100% by mass.

Mode 5.
A varnish comprising a copolymer according to any one of aspects 1 to 3, or a composition according to aspect 4, and (h) a solvent.

Mode 6.
Varnish according to aspect 5, wherein the solvent is MEK (methyl ethyl ketone).

Aspect 7.
A cured product of the aromatic vinyl compound-aromatic polyene copolymer according to any one of Embodiments 1 to 3.

Mode 8.
A cured product of the composition according to aspect 4.

Mode 9.
A cured product of the varnish according to aspect 5 or 6.

Aspect 10.
The cured body according to any one of aspects 7 to 9, which is an electrical insulating material.

Aspect 11.
A CCL substrate, FCCL substrate, interlayer insulating material, bonding sheet, or coverlay, comprising the cured body according to any one of aspects 7 to 9.

The aromatic vinyl compound-aromatic polyene copolymer according to the embodiment of the present invention, the composition containing the same, or the cured product or varnish made of the same provides a hard cured product and a low dielectric material having high solubility in solvents.

The compositions according to the invention are described in more detail below. In this specification, the term "sheet" also includes the concept of film. Further, even if the term "film" is used in this specification, the concept of "sheet" is also included. The term "composition" as used herein is a concept that includes varnish. That is, among the compositions, those that are particularly liquid are described as varnishes. As used herein, interlayer insulation includes the concept of bonding sheets or interlayer adhesives.

Numerical ranges in this specification include their lower and upper limits unless otherwise specified.

<Aromatic Vinyl Compound-Aromatic Polyene Copolymer>
The aromatic vinyl compound-aromatic polyene copolymer of the present invention is an aromatic vinyl compound-aromatic polyene copolymer that satisfies all of the following conditions (1) to (4).
(1) The copolymer has a number average molecular weight of 500 or more and less than 100,000.
(2) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and the content of the aromatic vinyl compound monomer units exceeds 70% by mass. It is preferably 71% by mass or more, more preferably 80% by mass or more.
(3) The aromatic polyene is one or more selected from polyenes having a plurality of vinyl groups and/or vinylene groups in the molecule and having 5 to 20 carbon atoms, and the vinyl group and/or vinylene group content derived from the aromatic polyene unit is 2 or more and less than 30, preferably 3 or more and less than 30 per number average molecular weight.
(4) One or more selected from olefin monomer units having 2 to 20 carbon atoms may be included, and the sum of the aromatic vinyl compound monomer units and the aromatic polyene monomer units and, if present, the olefin monomer units is 100% by mass.

The olefin monomer that may be included here is one or more selected from α-olefins having 2 to 20 carbon atoms and cyclic olefins having 5 to 20 carbon atoms, and is substantially free of oxygen, nitrogen, and halogen, and is a compound composed of carbon and hydrogen. Examples of α-olefins having 2 to 20 carbon atoms include ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decane, 1-dodecane, 4-methyl-1-pentene and 3,5,5-trimethyl-1-hexene. Examples of cyclic olefins having 5 to 20 carbon atoms include norbornene and cyclopentene. The olefin that can be preferably used is a combination of ethylene and an α-olefin other than ethylene or a cyclic olefin, or ethylene alone.

The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 to 20 carbon atoms, and examples thereof include styrene, paramethylstyrene, ethylstyrene (ethylvinylbenzene), paraisobutylstyrene, various vinylnaphthalenes, and various vinylanthracenes.

The aromatic polyene monomer is a polyene having a plurality of vinyl groups and/or vinylene groups in the molecule and having 5 to 20 carbon atoms, preferably a polyene having a plurality of vinyl groups in the molecule and having 5 to 20 carbon atoms, more preferably ortho-, meta-, and para-divinylbenzenes or mixtures thereof, divinylnaphthalene, divinylanthracene, p-2-propenylstyrene, p-3-butenylstyrene, etc. having an aromatic vinyl structure. , is a compound composed of carbon and hydrogen, substantially free of oxygen, nitrogen, and halogens. Bifunctional aromatic vinyl compounds such as 1,2-bis(vinylphenyl)ethane (abbreviation: BVPE) described in JP-A-2004-087639 can also be used. Among these, ortho-, meta-, and para-divinylbenzenes, or mixtures thereof, are preferably used, and most preferably, a mixture of meta-divinylbenzene and para-divinylbenzene. In this specification, these divinylbenzenes are referred to as divinylbenzenes. When divinylbenzenes are used as the aromatic polyene, they are preferable because they have high curing efficiency and are easy to cure.

The above-mentioned olefin, aromatic vinyl compound, and aromatic polyene monomers may contain other polar groups such as olefins containing oxygen atoms, nitrogen atoms, etc., aromatic vinyl compounds containing oxygen atoms, nitrogen atoms, etc., or aromatic polyenes containing oxygen atoms, nitrogen atoms, etc. The total mass of the monomers containing these polar groups is preferably 10% by mass or less, more preferably 3% by mass or less, of the total mass of the resin composition, and most preferably does not contain a monomer containing a polar group. By setting the amount to 10% by mass or less, the dielectric properties (low dielectric constant/low dielectric loss) of the cured product obtained by curing the present resin composition can be improved.

The present aromatic vinyl compound-aromatic polyene copolymer may preferably further satisfy the following condition (5).
(5) The content of olefin monomer units is 1% by mass or more, and the total amount of olefin monomer units, aromatic vinyl compound monomer units and aromatic polyene monomer units is 100% by mass.

The number average molecular weight (Mn) of the copolymer is 500 or more and less than 100,000. The number average molecular weight of 500 or more and less than 100,000 in the present invention means that the molecular weight in terms of standard polystyrene obtained by GPC (gel permeation chromatography) falls within that range.

The number average molecular weight of the copolymer may be preferably 1,000 or more and 80,000 or less, more preferably 1,000 or more and 50,000 or less, and still more preferably 1,000 or more and 40,000 or less.

The content of the aromatic vinyl compound monomer unit contained in the present copolymer exceeds 70% by mass, preferably 71% by mass or more, and more preferably 80% by mass or more, when the total of the aromatic vinyl compound monomer unit, the aromatic polyene monomer unit, and the optionally present olefin monomer unit is 100% by mass. When the content of the aromatic vinyl compound monomer units exceeds 70% by mass, the finally obtained cured body of the present aromatic vinyl compound-aromatic polyene copolymer alone can have a tensile modulus of 1000 MPa or more at 25°C, and the cured body of the composition mainly composed of the present aromatic vinyl compound-aromatic polyene copolymer can easily have a tensile modulus of 100 MPa or more at 25°C. Furthermore, the present aromatic vinyl compound-aromatic polyene copolymer has a high solubility in solvents such as methyl ethyl ketone (MEK), making it easy to produce varnishes using methyl ethyl ketone as a solvent.

Also, the content of the aromatic vinyl compound monomer unit contained in the present copolymer may be 98% by mass or less, 95% by mass or less, 92% by mass or less, or 90% by mass or less with respect to the above criteria. When the aromatic vinyl compound monomer unit is 98% by mass or less, it becomes easier to adjust the hardness of the cured product to an appropriate level.

In the present copolymer, the content of vinyl groups and/or vinylene groups derived from aromatic polyene units, preferably the content of vinyl groups is 2 or more and less than 30, preferably 3 or more and less than 30 per number average molecular weight. If the content of the vinyl group and/or vinylene group is less than 2, the cross-linking efficiency is low, making it difficult to obtain a cured product with a sufficient cross-linking density. The vinyl group content derived from the aromatic polyene unit (divinylbenzene unit) per number average molecular weight in the copolymer can be obtained by comparing the number average molecular weight (Mn) in terms of standard polystyrene determined by a GPC (gel permeation chromatography) method known to those skilled in the art with the vinyl group content derived from the aromatic polyene unit obtained by ¹ H-NMR measurement. As an ^example , when the vinyl group content derived from the aromatic polyene unit (divinylbenzene unit) in the copolymer is 0.88% by mass and the standard polystyrene conversion number average molecular weight (Mn) by GPC measurement is 38300, the molecular weight of the vinyl group derived from the aromatic polyene unit in the number average molecular weight is 336, which is the product of these, and this is the formula weight 2 of the vinyl group. Dividing by 7 gives 12.5. That is, the vinyl group content derived from the aromatic polyene unit per number average molecular weight in the present copolymer is required to be 12.5. The assignment of peaks obtained in ¹ H-NMR measurements of copolymers is known from the literature. A method for determining the composition of a copolymer from comparison of peak areas obtained by ¹ H-NMR measurement is also known. Furthermore, it is also possible to improve the accuracy of the composition by adding the data of the peak areas and their ratios of the ¹³ C-NMR spectrum measured in a known quantitative mode to the present ¹ H-NMR measurement method. Furthermore, the composition can also be obtained from the data of the peak areas and their ratios in the ¹³ C-NMR spectrum measured in a known quantitative mode. Also, in this specification, the content of divinylbenzene units in the copolymer is determined from the peak intensity of the vinyl group derived from the divinylbenzene units (by ¹ H-NMR measurement). That is, from the content of vinyl groups derived from divinylbenzene units, the content of divinylbenzene units is determined assuming that one vinyl group is a vinyl group derived from one divinylbenzene unit in the copolymer.

In the present copolymer, the content of the olefin monomer unit may be preferably 0% by mass or more or 1% by mass or more, more preferably 0% by mass or more and less than 30% by mass or 1% by mass or more and less than 30% by mass, and still more preferably 1% by mass or more and 20% by mass or less. The total amount of the olefin monomer units, the aromatic vinyl compound monomer units and the aromatic polyene monomer units is 100% by mass. When the content of the olefin monomer unit is 1% by mass or more, the toughness (elongation) and impact resistance of the finally obtained cured product are improved, and cracking during curing and cracking during the heat cycle test of the cured product are less likely to occur. In particular, from the viewpoint of further improving the toughness (elongation) and impact resistance of the cured product, the content of the olefin monomer unit is preferably more than 5% by mass and less than 30% by mass. In another embodiment, the copolymer may be free of olefinic monomer units.

<Method for Producing Aromatic Vinyl Compound-Aromatic Polyene Copolymer>
The aromatic vinyl compound-aromatic polyene copolymer of the present invention can be produced by copolymerizing an aromatic vinyl compound, an aromatic polyene, and optionally an olefin monomer through coordination polymerization. For example, it is preferable to use a single-site coordination polymerization catalyst composed of a transition metal compound and a cocatalyst described in JP-A-2009-161743, JP-A-2010-280771, and International Publication No. 00/037517, because an aromatic vinyl compound-aromatic polyene copolymer can be efficiently produced.

The chemical structure of the present copolymer obtained using a coordination polymerization catalyst consisting of a combination of a transition metal compound and a co-catalyst is characterized in that it does not contain a specific structure. That is, the copolymer obtained by the cationic polymerization method according to the prior art has, for example, a polymer terminal structure containing an alicyclic ring as described in WO 2018/181842 above, but the copolymer according to the embodiment of the present invention has a remarkable difference that it does not have such a structure. Due to this difference, the present invention provides the effect of facilitating molecular design.

The polymer terminal structure contained in the aromatic vinyl compound-aromatic polyene copolymer of the present invention can be clarified qualitatively or quantitatively by known methods using ¹ H-NMR and ¹³ C-NMR. In the aromatic vinyl compound-aromatic polyene copolymer of the present invention, the polymer terminal structure contained in the styrene-divinylbenzene copolymer comprising styrene as a general aromatic vinyl compound and divinylbenzene as the aromatic polyene is one of the structures represented by E-1 to E-6 below, or any combination thereof. In the aromatic vinyl compound-aromatic polyene copolymer of the present invention, an ethylene-styrene-divinylbenzene copolymer composed of styrene as a general aromatic vinyl compound, divinylbenzene as an aromatic polyene, and ethylene as an olefin as another component is one of the structures represented by the following chemical formulas E-1 to E-6, or any combination thereof.

In the above formula, P represents the polymer structural residue of the aromatic vinyl compound-aromatic polyene copolymer, and Z represents hydrogen, a vinyl group, or a vinylene group.

About half of the polymer terminal structures are generally composed of E-1 and E-3, and substantially most of them are E-1 and E-3. In addition, E-5 may also be included. These structures are terminals having a saturated structure, and therefore the aromatic vinyl compound-aromatic polyene copolymer of the present invention essentially has the feature of high durability such as heat resistance. The structure of the polymerization initiation terminal changes depending on factors such as whether the first monomer insertion occurs with respect to the metal-hydrogen bond, whether the first monomer insertion occurs with the metal-alkyl group structure, whether the first monomer insertion occurs with ethylene, styrene, or divinylbenzene, and when the first monomer is styrene or divinylbenzene, whether it is 2,1 insertion or 1,2 insertion.

The structure of the chain transfer end (polymerization termination end) of the polymer growing chain of the polymer terminal structure is generally E-2 and E-6, and the remaining E-5, E-4, E-1 and E-3 are also included. The ratio of the structure of the chain transfer end changes depending on whether the chain transfer occurs by hydrogen abstraction at the beta position, by chain transfer to another coordination monomer, by chain transfer to the alkylaluminum co-catalyst component, or by chain transfer to a chain transfer agent such as hydrogen. That is, the polymer terminal structure of the aromatic vinyl compound-aromatic polyene copolymer which may contain an olefin according to the present invention has many saturated types E-1, E-3, and E-5, and unsaturated types E-4 and E-6 have a small proportion. Even when an olefin other than ethylene, an aromatic vinyl compound other than styrene, or an aromatic polyene other than divinylbenzene is used, each unit of ethylene, styrene, and divinylbenzene in the terminal structures of E-1 to E-6 is replaced with a monomer other than that.

In any case, the polymer terminal structure of the aromatic vinyl compound-aromatic polyene copolymer which may contain an olefin of the present invention consists of one or more of the above structures E-1 to E-6, and other structures are substantially not included. Since the aromatic vinyl compound-aromatic polyene copolymer which may contain an olefin according to the present invention is obtained by specific coordination polymerization, it is a copolymer having a relatively low degree of polymer chain branching and high linearity.

On the other hand, as an example of a polymer obtained by cationic polymerization, a terminal structure containing an alicyclic ring formed by a chain transfer such as an electrophilic substitution reaction of a carbocation at a polymer growth terminal to an aromatic ring of an aromatic monomer, which is described in International Publication No. 2018/181842 relating to the prior art, is not included in the copolymer according to the present invention. On the other hand, the aromatic vinyl compound-aromatic polyene copolymer described in WO 2018/181842 contains a very large number of terminal structures per polymer molecule due to its dendritic and multibranched structure, and the terminal structures described are mostly unsaturated structures of vinyl groups and vinylene groups with various structures due to cationic polymerization, and there is a problem in heat resistance stability. It has a problem of deteriorating heat resistance stability. If a large amount of unsaturated groups such as vinylene groups are present in the cured product, they will bond or react with oxygen in the air, resulting in an increase in the dielectric constant and dielectric loss tangent of the cured product, which is not preferable.

Examples of the aromatic vinyl compound-aromatic polyene copolymer (which may contain an olefin) in the present copolymer include styrene-divinylbenzene copolymer, ethylene-styrene-divinylbenzene copolymer, ethylene-propylene-styrene-divinylbenzene copolymer, ethylene-1-hexene-styrene-divinylbenzene copolymer, and ethylene-1-octene-styrene-divinylbenzene copolymer.

In addition to the present copolymer, the composition of the present invention may further contain (a) a curing agent, (b) one or more resins selected from hydrocarbon elastomers, polyphenylene ether resins, and aromatic polyene resins, (c) a monomer, and (d) one or more selected from another olefin-aromatic vinyl compound-aromatic polyene copolymer that satisfies all of the following conditions (i) to (iv).
(i) The copolymer has a number average molecular weight of 500 or more and less than 100,000.
(ii) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and the content of aromatic vinyl compound monomer units is 70% by mass or less.
(iii) The aromatic polyene is one or more selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and/or vinylene groups in the molecule, and the content of vinyl groups and/or vinylene groups derived from the aromatic polyene units is 1.5 or more and less than 20 per number average molecular weight.
(iv) The olefin is one or more selected from olefins having 2 to 20 carbon atoms, the content of olefin monomer units is 30% by mass or more, and the total of the olefin monomer units, aromatic vinyl compound monomer units and aromatic polyene monomer units is 100% by mass.

The other olefin-aromatic vinyl compound-aromatic polyene copolymer as an optional additional component described above may have the same characteristics as the present copolymer, except for the content of aromatic vinyl compound monomer units.

<Curing agent>
As the curing agent that can be used in the composition of the present invention, it is possible to use known curing agents that can be used for conventional polymerization or curing of aromatic polyenes and aromatic vinyl compounds. Examples of such curing agents include radical polymerization initiators (radical generators), cationic polymerization initiators, and anionic polymerization initiators, and preferably radical polymerization initiators can be used. More preferred are organic peroxides, azo polymerization initiators, etc., which can be freely selected according to the application and conditions. Catalogs with organic peroxides can be found on the NOF website, e.g.
https://www.nof.co.jp/business/chemical/chemical-product01
can be downloaded from Organic peroxides are also described in the catalogs of Fuji Film Wako Pure Chemical Co., Ltd. and Tokyo Kasei Kogyo Co., Ltd., etc. Curing agents for use in the present invention are available from these companies. A known photopolymerization initiator using light, ultraviolet rays, or radiation can also be used as a curing agent. Photopolymerization initiators include radical photopolymerization initiators, cationic photopolymerization initiators, and anionic photopolymerization initiators. Such photoinitiators are available, for example, from Tokyo Chemical Industry Co., Ltd. Furthermore, curing by radiation or electron beam itself is also possible. It is also possible to perform cross-linking and curing by thermal polymerization of contained raw materials without containing a curing agent.

The amount of the curing agent used is not particularly limited, but is generally preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the resin composition. It is preferable that the resin composition excludes a curing agent and a solvent. When using a curing agent such as a peroxide or an azo polymerization initiator, the curing treatment is performed at an appropriate temperature and time in consideration of its half-life. The conditions in this case are arbitrary according to the curing agent, but generally a temperature range of about 50°C to 200°C is suitable.

The composition or varnish according to the embodiment of the present invention can contain the sum of component (b), that is, "one or more resins selected from hydrocarbon elastomers, polyphenylene ether resins, and aromatic polyene resins" and component (d), that is, "another olefin-aromatic vinyl compound-aromatic polyene copolymer", preferably in the range of 1 to 200 parts by mass with respect to 100 parts by mass of the copolymer. By adding component (b) or component (d), the effect of improving the mechanical properties necessary for various purposes of use of the cured product obtained from the present varnish can be obtained.

<Hydrocarbon elastomer>
The amount of the hydrocarbon-based elastomer that may be contained in the composition according to the embodiment of the present invention is preferably 1 to 200 parts by mass, more preferably 1 to 100 parts by mass, and most preferably 1 to 50 parts by mass, based on 100 parts by mass of the present copolymer (that is, another olefin-aromatic vinyl compound-aromatic polyene copolymer which is an optional additional component is excluded). The hydrocarbon elastomer that can be suitably used in the composition of the present invention preferably has a number average molecular weight of 100 to 100,000, more preferably 500 to 100,000, and even more preferably 1,000 to 4,500. The hydrocarbon-based elastomer that can be suitably used in the composition of the present invention is preferably one or more elastomers selected from ethylene-based or propylene-based elastomers, conjugated diene-based polymers, aromatic vinyl compound-conjugated diene-based block copolymers or random copolymers, and hydrides (hydrogenated products) thereof. Ethylene-based elastomers include ethylene-α-olefin copolymers such as ethylene-octene copolymers and ethylene-1-hexene copolymers, EPR, and EPDM. Propylene-based elastomers include atactic polypropylene, low stereoregular polypropylene, and propylene-α-olefin copolymers such as propylene-1-butene copolymers. These hydrocarbon elastomers may be modified such as by introducing functional groups with maleic anhydride or other compounds.

Conjugated diene polymers include polybutadiene and 1,2-polybutadiene. Examples of aromatic vinyl compound-conjugated diene block copolymers or random copolymers and hydrides (hydrogenated products) thereof include SBS, SIS, SEBS, SEPS, SEEPS and SEEBS. The 1,2-polybutadiene that can be preferably used is available from Nippon Soda Co., Ltd. under the product names of liquid polybutadiene: product names B-1000, 2000 and 3000, for example. As a copolymer containing a 1,2-polybutadiene structure that can be suitably used, "Ricon 100" manufactured by TOTAL CRAY VALLEY can be exemplified. These conjugated diene polymers and their hydrides may be modified such as by introducing functional groups with maleic anhydride or other compounds. Among the conjugated diene-based polymers, polymers containing no vinylene groups or less vinylene groups in the main chain are preferred. This is because the vinylene group in the main chain tends to remain in the cured product even after curing, and the vinylene group reacts with oxygen in the air to generate a polar group containing oxygen, which tends to increase the dielectric constant and dielectric loss values. From this point of view, a 1,4-polybutadiene copolymer is not suitable as the conjugated diene polymer, and a 1,2-polybutadiene polymer or copolymer containing a 1,2-polybutadiene structure can be preferably used. Further, from this point of view, it is preferable to use various hydrogenated polymers in which the vinylene groups are hydrogenated and their content is greatly reduced. Hydrogenated polymers of conjugated diene polymers include hydrogenated SBR, SEBS, SEPS, SEEPS and SEEBS, preferably hydrogenated polymers of conjugated diene polymers having methyl-substituted styrene. When one or more resins selected from these hydrocarbon-based elastomers are liquid (approximately 300,000 mPa s or less) at room temperature (25°C), the composition of the present invention is used in an amount of preferably 150 parts by mass or less, more preferably 1 to 30 parts by mass, and most preferably 1 to 20 parts by mass, based on 100 parts by mass of the copolymer, from the viewpoint of handling and molding processability (handlability as a thermoplastic resin) in an uncured state.

<Polyphenylene ether>
As the polyphenylene ether (also referred to as "polyphenylene ether-based resin"), commercially available known polyphenylene ethers can be used. The number average molecular weight of the polyphenylene ether is arbitrary, and is preferably 10,000 or less, most preferably 5,000 or less, in consideration of the molding processability of the composition. The number average molecular weight is preferably 500 or more.

In the case of addition for the purpose of curing the composition of the present invention, it is preferable that the terminal of the molecule is modified with a functional group. In the case of addition for the purpose of curing the composition of the present invention, it is preferable that one molecule has a plurality of functional groups. For example, modified polyphenylene ether is preferred. The functional group includes a radically polymerizable functional group and a functional group such as an epoxy group, preferably a radically polymerizable functional group. A vinyl group is preferable as the radically polymerizable functional group. The vinyl group is preferably one or more selected from the group consisting of an allyl group, a (meth)acryloyl group and an aromatic vinyl group, more preferably one or more selected from the group consisting of a (meth)acryloyl group and an aromatic vinyl group, and most preferably an aromatic vinyl group. That is, in the composition of the present invention, a bifunctional polyphenylene ether in which both ends of the molecular chain are modified with radically polymerizable functional groups is particularly preferred. Such preferred polyphenylene ethers include SABIC's Noryl (trademark) SA9000 (modified polyphenylene ether having methacryloyl groups at both ends, number average molecular weight of 2200) and Mitsubishi Gas Chemical Co., Ltd.'s bifunctional polyphenylene ether oligomer (OPE-2St, modified polyphenylene ether having vinylbenzyl groups at both ends, number average molecular weight of 1200), and the like. In addition, allylated PPE manufactured by Asahi Kasei Corp., aromatic polyethers manufactured by JSR Corp. (ELPAC HC-F series), etc. can also be used. Among these, a bifunctional polyphenylene ether oligomer (OPE-2St) manufactured by Mitsubishi Gas Chemical Co., Ltd. can be preferably used. The amount of polyphenylene ether used in the composition of the present invention is preferably 1 to 200 parts by mass, more preferably 1 to 100 parts by mass, per 100 parts by mass of the copolymer.

<Aromatic polyene resin>
The aromatic polyene-based resin includes a divinylbenzene-based reactive polybranched copolymer (PDV) manufactured by Nippon Steel Chemical & Materials. Such a PDV is described, for example, in the document "Synthesis of Polyfunctional Aromatic Vinyl Copolymer and Development of New IPN-type Low Dielectric Loss Material Using Same" (Masao Kawabe, Journal of Electronics Packaging Society p125, Vol.12 No.2 (2009)). The amount of the aromatic polyene resin used in the composition of the present invention is preferably 1 to 200 parts by mass, more preferably 1 to 100 parts by mass, and most preferably 1 to 50 parts by mass, based on 100 parts by mass of the copolymer. Use of the aromatic polyene-based resin in an amount within these ranges is preferable in order to prevent a decrease in adhesion to other members and a decrease in toughness.

<monomer>
The monomer that the composition of the present invention may contain is preferably 100 parts by weight or less per 100 parts by weight of the copolymer. The present resin composition may be substantially free of monomers. A monomer is a monomer that can be polymerized by either radical polymerization, cationic polymerization, or anionic polymerization, preferably a monomer that can be radically polymerized. Its molecular weight is preferably 5000 or less, preferably less than 5000, more preferably 1000 or less, more preferably less than 1000, still more preferably 500 or less, still more preferably less than 500, the "aromatic vinyl compound" and "aromatic polyene", and may also contain an "aromatic vinylene compound" as appropriate. An aromatic vinylene compound is a compound having both a single aromatic ring or multiple condensed aromatic rings having 9 to 30 carbon atoms and a vinylene group. Examples of such aromatic vinylene compounds include indenes, beta-substituted styrenes and acenaphthylenes. Examples of the indenes include indene, various alkyl-substituted indenes and phenyl-substituted indenes. Beta-substituted styrenes include β-alkyl-substituted styrenes such as β-methylstyrene, or phenyl-substituted styrenes. Acenaphthylenes include acenaphthylene, various alkyl-substituted acenaphthylenes, and various phenyl-substituted acenaphthylenes. As the aromatic vinylenes, the compounds exemplified above may be used alone, or two or more of them may be used in combination. The aromatic vinylenes preferably have a boiling point of 175°C or higher at normal pressure. Acenaphthylene is most preferable from the viewpoint of industrial availability and radical polymerizability. Preferably, the monomer can be selected from "aromatic vinyl compound", "aromatic polyene", or "aromatic vinylene". Preferred are the aforementioned "aromatic vinyl compound" and "aromatic polyene". Also more preferably, the monomer may be the following "polar monomer".

<Polar monomer>
The polar monomer that the composition of the present invention may contain is preferably 100 parts by weight or less per 100 parts by weight of the copolymer. The present resin composition may be substantially free of polar monomers. A polar monomer is a monomer having one or more atoms selected from oxygen, nitrogen, phosphorus, and sulfur in the molecule, and a polar monomer that can be suitably used has a molecular weight of preferably less than 5000, more preferably less than 1000, and even more preferably less than 500. A polar monomer that can be suitably used in the resin composition of the present invention is preferably a polar monomer that can be polymerized by a radical polymerization initiator. Polar monomers include various maleimides, bismaleimides, maleic anhydride, triallyl isocyanurate, glycidyl (meth)acrylate, tri(meth)acryl isocyanurate, trimethylolpropane tri(meth)acrylate, and the like. Maleimides and bismaleimides that can be used in the present invention are described in, for example, International Publication No. 2016/114287 and Japanese Patent Application Laid-Open No. 2008-291227, and can be purchased from, for example, Daiwa Kasei Kogyo Co., Ltd., Nippon Kayaku Co., Ltd., Designer molecules inc. A bismaleimide resin "SLK" manufactured by Shin-Etsu Chemical Co., Ltd. can also be used. These maleimide group-containing compounds are preferably bismaleimides from the viewpoints of solubility in organic solvents, high frequency characteristics, high adhesion to conductors, moldability of prepreg, and the like. These maleimide group-containing compounds may be used as polyaminobismaleimide compounds from the viewpoints of solubility in organic solvents, high frequency characteristics, high adhesion to conductors, moldability of prepreg, and the like. A polyaminobismaleimide compound is obtained, for example, by Michael addition reaction between a compound having two maleimide groups at the terminals and an aromatic diamine compound having two primary amino groups in the molecule. When trying to obtain high cross-linking efficiency with the addition of a small amount, it is preferable to use a polar monomer having a polyfunctional group of two or more functional groups, such as bismaleimides, triallyl isocyanurate (TAIC), and trimethylolpropane tri(meth)acrylate. The amount of the polar monomer used in the resin composition of the present invention is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the copolymer. By using an amount within this range, it is possible to obtain the effect of preventing the dielectric constant and dielectric loss tangent of the obtained cured product from becoming too high.

<Another olefin-aromatic vinyl compound-aromatic polyene copolymer>
The composition of the present invention (d) may contain one or more selected from olefin-aromatic vinyl compound-aromatic polyene copolymers other than the present copolymer, which satisfy all of the following conditions (i) to (iv).
(i) The copolymer has a number average molecular weight of 500 or more and less than 100,000.
(ii) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and the content of aromatic vinyl compound monomer units is 70% by mass or less.
(iii) The aromatic polyene is one or more selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and/or vinylene groups in the molecule, and the content of vinyl groups and/or vinylene groups derived from the aromatic polyene units is 1.5 or more and less than 20 per number average molecular weight.
(iv) The olefin is one or more selected from olefins having 2 to 20 carbon atoms, the content of olefin monomer units is 30% by mass or more, and the total of the olefin monomer units, aromatic vinyl compound monomer units and aromatic polyene monomer units is 100% by mass.
Such olefin-aromatic vinyl compound-aromatic polyene copolymers that satisfy all other specific conditions are described, for example, in WO2021/112087, WO2021/112088, and WO2022/014599. An olefin-aromatic vinyl compound-aromatic polyene copolymer that satisfies all such other specific conditions is flexible and exhibits a low dielectric constant and a low dielectric loss tangent, so it is suitable because it can be combined with the aromatic vinyl compound-aromatic polyene copolymer of the present invention to form a composition to provide a cured product with a low dielectric constant and a low dielectric loss tangent that covers a wide range of physical properties.

Specifically, for example, with respect to 100 parts by mass of the aromatic vinyl compound-aromatic polyene copolymer of the present invention, the other olefin-aromatic vinyl compound-aromatic polyene copolymer is preferably added in an amount of 1 to 200 parts by mass, particularly preferably 50 to 200 parts by mass. As used herein, uncured includes the concept of semi-cured. In this specification, the uncured composition is in a state in which the composition itself exhibits thermoplasticity (i.e., a property in which molding such as sheeting is possible under molding conditions that do not cause curing), and indicates a state in which curing is possible by applying appropriate curing conditions (heating, pressure, etc.) after molding. Therefore, it is particularly useful as an interlayer insulating sheet or bonding sheet that must be stored and transported in an uncured state. The glass transition temperature of the aromatic vinyl compound-aromatic polyene copolymer of the present invention can be confirmed to be in the range of 30°C to 100°C by a known measuring method. The other olefin-aromatic vinyl compound-aromatic polyene copolymer described above can be confirmed to have a glass transition temperature in the range of -100 to 30°C by a similar measurement method. Therefore, the composition as described above has a plurality of glass transition temperatures both in the range of 30°C to 100°C and in the range of -100°C to 30°C in an uncured state. Examples of known measurement methods include differential scanning calorimetry (DSC) and dynamic viscoelasticity measurement (DMA).

Furthermore, the composition of the present invention may contain one or more selected from the following (e) to (g).
(e) filler (f) flame retardant (g) surface modifier

<Filler>
A known inorganic or organic filler can be added as required. These fillers are added for the purpose of controlling the coefficient of thermal expansion, controlling the thermal conductivity, and reducing the price, and the amount used is arbitrary depending on the purpose. In particular, when adding an inorganic filler, it is preferable to use a known surface modifier such as a silane coupling agent. In particular, when aiming at a resin composition excellent in low dielectric constant and low dielectric loss, which is one of the objects of the present invention, the inorganic filler is preferably one or more of boron nitride (BN) or silica, more preferably silica. As silica, fused silica is preferred. From the viewpoint of low dielectric properties, preferably 500 parts by mass or less and less than 500 parts by mass, more preferably 400 parts by mass or less and less than 400 parts by mass of the filler is used with respect to 100 parts by mass of the copolymer. Furthermore, in order to improve low dielectric properties (low dielectric constant, low dielectric loss tangent), a hollow filler or a filler having a shape with many voids may be added.

It is also possible to use organic fillers such as high-molecular-weight polyethylene or ultra-high-molecular-weight polyethylene instead of inorganic fillers. From the viewpoint of heat resistance, the organic filler itself is preferably crosslinked, and is preferably blended in the form of fine particles or powder. These organic fillers can suppress increases in dielectric constant and dielectric loss tangent.

On the other hand, by mixing and dispersing a high dielectric constant insulator filler having a dielectric constant at 1 GHz of preferably 4 to 10000, more preferably 5 to 10000, in the resin composition of the present invention, the dielectric loss tangent (dielectric loss) can be suppressed. By increasing the dielectric constant of the film made of the insulating hardening material, it becomes possible to reduce the size of the circuit and increase the capacity of the capacitor, which contributes to the reduction of the size of high-frequency electric parts. A high dielectric constant, low dielectric loss tangent insulating layer is suitable for applications such as capacitors, inductors for resonant circuits, filters, and antennas. Examples of the high dielectric constant insulator filler used in the present invention include inorganic fillers and metal particles subjected to insulation treatment. Specific examples are known high dielectric constant inorganic fillers such as barium titanate and strontium titanate, and other examples are specifically described in JP-A-2004-087639.

<Flame retardant>
Flame retardants may be used in the compositions of the present invention. From the viewpoint of maintaining a low dielectric constant and a low dielectric loss tangent, preferred flame retardants are known organic phosphorous compounds such as phosphoric acid esters or condensates thereof, known brominated flame retardants, and red phosphorus. Among phosphoric acid esters, compounds having a plurality of xylenyl groups in the molecule are particularly preferred from the viewpoint of flame retardancy and low dielectric loss tangent.

Furthermore, antimony compounds such as antimony trioxide, antimony tetroxide, antimony pentoxide, and sodium antimonate, or nitrogen-containing compounds such as melamine, triallyl-1,3,5-triazine-2,3,4-(1H,3H,5H)-trione, and 2,4,6-triaryloxy-1,3,5-triazine may be added as flame retardant aids in addition to the flame retardant. The total amount of these flame retardants and auxiliary flame retardants is usually preferably 1 to 100 parts by mass with respect to 100 parts by mass of the resin composition. Further, 30 to 200 parts by mass of the polyphenylene ether (PPE)-based resin having a low dielectric constant and excellent flame retardancy may be used with respect to 100 parts by mass of the flame retardant.

<Surface modifier>
The composition of the present invention contains a surface modifying agent for the purpose of improving adhesion to a copper foil for wiring. In particular, the purpose is to increase the adhesion strength (peel strength) to the smooth surface of the copper foil. The amount of the surface modifier used is in the range of 0.001 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, most preferably 0.01 to 1 part by mass, based on 100 parts by mass of the olefin-aromatic vinyl compound-aromatic polyene copolymer. If the amount of the surface modifier used is less than 10 parts by mass, the dielectric constant and dielectric loss tangent of the cured product obtained from the composition will be low. A known surface modifier can be used in the present invention. Examples of such surface modifiers include silane-based surface modifiers (also known as silane coupling agents), titanate-based surface modifiers, and isocyanate-based surface modifiers. Preferably, silane-based surface modifiers are used. One or more of these surface modifiers may be used. Such silane-based surface modifiers are available from Shin-Etsu Chemical Co., Dow Corning, and Evonik.

The composition of the present invention may further comprise (h) a solvent. Among the compositions of the present invention, those that are particularly liquid by containing a solvent are called varnishes.

<Solvent>
A suitable solvent (solvent) may be added to the composition of the present invention, if necessary. Moreover, the usage amount is not particularly limited. A solvent is used to adjust the viscosity and fluidity of the composition. In particular, when the resin composition of the present invention is in the form of varnish, a solvent is preferably used. As the solvent, if the boiling point under atmospheric pressure is high, that is, if the volatility is low, the thickness of the coated film will be uniform. A preferable boiling point is approximately 75° C. or higher, more preferably 130° C. or higher and 300° C. or lower under atmospheric pressure. Examples of solvents include cyclohexane, cyclohexanone, methyl ethyl ketone (MEK), toluene, ethylbenzene, xylene, mesitylene, tetralin, acetone, limonene, mixed alkanes, and mixed aromatic solvents. The amount of the solvent used in the composition of the present invention is arbitrary, but is preferably 5 to 500 parts by mass, more preferably 10 to 300 parts by mass, and most preferably 50 to 150 parts by mass, relative to 100 parts by mass of the copolymer.

When using raw materials with low solubility in toluene or other aromatic solvents, such as specific bismaleimide, as the constituents of the composition of the present invention, methyl ethyl ketone (MEK) can be used as the solvent. In that case, the aromatic vinyl compound-aromatic polyene copolymer of the present invention is preferred because of its high solubility in methyl ethyl ketone.

The composition and varnish of the present invention can contain additives that are commonly used in resins, such as antioxidants, weathering agents, light stabilizers, lubricants, compatibilizers, and antistatic agents, as long as the effects and objects of the present invention are not impaired. The composition and varnish of the present invention can be obtained by mixing, dissolving, or melting the various additives described above, and any known methods for mixing, dissolving, and melting can be employed.

The composition of the present invention can be mixed by a known kneading method such as a twin-screw kneader, various rolls, various kneaders, and the like. When the composition is a varnish, it can be mixed by adding to the varnish and stirring.

<Varnish>
The varnish of the present invention can exhibit a viscous liquid state by adjusting the composition and molecular weight of the copolymer to be used, adding a certain amount or more of a liquid monomer or solvent within the scope of the present invention, or adding a liquid flame retardant, and can exhibit a viscous liquid state by heating at room temperature or 100 ° C. or less. It is 500 mPa·s or less. Specifically, a molded body can be obtained by applying, impregnating, filling, or dripping onto another material by an appropriate method and removing the solvent. Furthermore, the desired cured product can be obtained by curing with heat or light. Such properties can be obtained by various transfer molding (press-fit molding), coating on or between substrates and semiconductor device materials, extrusion lamination, or spin coating to form sheets or films, and then curing to form an insulating coating or insulating layer. In addition, the polymerization liquid obtained when copolymerizing the aromatic vinyl compound-aromatic polyene copolymer of the present invention (generally containing a solvent such as toluene, ethylbenzene, cyclohexane, and methylcyclohexane, a residual monomer such as styrene and divinylbenzene, a residual monomer such as an olefin monomer, a catalyst, and a co-catalyst component) can be used as a varnish as it is. Alternatively, the varnish can also be obtained by distilling off part or all of the solvent and residual monomers from the polymer solution under reduced pressure and diluting with the solvent as necessary. That is, the varnish of the present invention may contain residual monomers during polymerization and solvents used in polymerization.

<Molded body>
The shape of the molded article obtained from the composition of the present invention is arbitrary. These compositions can exhibit thermoplastic properties. Therefore, under conditions that do not cause cross-linking, a known molding method for thermoplastic resins, such as extrusion molding, injection molding, press molding, inflation molding, etc., in a substantially uncured state, can be molded into shapes such as sheets, tubes, strips, and pellets. In a certain embodiment, it is possible to obtain the effect that the molded article has less self-adhesiveness (tackiness). The molded body can then be crosslinked (cured). For example, when the composition is a varnish, it is generally formed into a sheet or film by removing the solvent by heating, depressurization, air drying, etc. after coating it on a substrate. Uncured sheets and films can be obtained by these methods. A composite can also be obtained by impregnating a porous substrate, woven fabric, or non-woven fabric with the varnish of the present invention and removing the solvent. For example, a hemispherical shape can be formed by dropping the solution onto the substrate and removing the solvent.
The sheet may be uncured (semi-cured) to the extent that the sheet shape can be maintained, or may be fully cured. The degree of hardening of the composition can be quantitatively measured by a known dynamic viscoelasticity measurement method (DMA, Dynamic Mechanical Analysis).

<Curing>
The composition and varnish of the present invention, and the molded article obtained from them can be cured by a known method with reference to the curing conditions (temperature, time, pressure) of the raw materials and curing agents contained therein. When the curing agent used is a peroxide, the curing conditions can be determined with reference to the half-life temperature and the like disclosed for each peroxide.

<Hardened body obtained from composition, cured body of molded body>
The cured product obtained from the composition of the present invention is sufficiently cured, and the gel content measured according to ASTM is preferably 90% by mass or more, more preferably more than 90% by mass. In the measurement range of 10 to 50 GHz, particularly preferably at 10 GHz, the dielectric constant of the cured product is preferably 3.0 to 2.0, more preferably 2.8 to 2.0, and most preferably 2.5 to 2.0. The dielectric loss tangent is preferably 0.003 or less and 0.0005 or more, more preferably 0.002 or less and 0.0005 or more. The volume resistivity of the obtained cured product is preferably 1×10 ¹⁵ Ω·cm or more, and the water absorption is preferably 0.1% by mass or less, more preferably less than 0.1% by mass, as an electrically insulating material. These values are particularly preferable values for an electrical insulating material for high frequencies of 3 GHz or higher, for example.

The cured product obtained from the copolymer or composition of the present invention is particularly suitable as an electrical insulating material for high-frequency signals, and these cured products can be suitably used for CCL substrates, FCCL substrates, interlayer insulating materials (bonding sheets), or coverlays. The present invention also relates to CCL substrates, FCCL substrates, interlayer insulating materials (bonding sheets), or coverlays made of the present copolymers or compositions containing the same.

EXAMPLES The present invention will be described below with reference to examples, but the present invention should not be construed as being limited to the following examples.

The copolymers obtained in Synthesis Examples and Comparative Synthesis Examples were analyzed by the following means.

The content of vinyl group units derived from ethylene, styrene, and divinylbenzene in the copolymer was determined by ¹ H-NMR from peak area intensities attributed to each. Samples were dissolved in heavy 1,1,2,2-tetrachloroethane and measurements were made at 80-130°C.

As for the molecular weight, GPC (gel permeation chromatography) was used to determine the number average molecular weight (Mn) in terms of standard polystyrene. Measurement was performed under the following conditions.

Column: Two TSK-GEL Multipore HXL-M φ7.8×300 mm (manufactured by Tosoh Corporation) were connected in series and used.
Column temperature: 40°C
Solvent: THF
Liquid sending flow rate: 1.0 ml/min.
Detector: RI detector

<Gel content>
The gel fraction was determined as boiling toluene insolubles according to ASTM D2765-84.

<Water absorption rate>
According to ASTM D570-98, the water absorption was measured after being immersed in pure water at 23° C. for 24 hours.

<Dielectric constant and dielectric loss (dielectric loss tangent)>
Permittivity and dielectric loss tangent were measured using a cavity resonator perturbation method (8722ES network analyzer manufactured by Agilent Technologies, cavity resonator manufactured by Kanto Denshi Applied Development Co., Ltd.) using a 1 mm × 1.5 mm × 80 mm sample cut from a sheet at 23 ° C. and 10 GHz.

<Tensile modulus>
In accordance with JIS K-6251: 2017, the cured body of the composition according to each example and comparative example was molded into a film sheet with a thickness of about 1 mm, cut into a No. 2 dumbbell No. 1/2 type test piece shape, and Tensilon UCT-1T manufactured by Orientec Co., Ltd. It was measured at 25 ° C. and a tensile speed of 500 mm / min to determine the tensile modulus.

<Storage modulus>
Using a dynamic viscoelasticity measuring device (TA Instruments Co., formerly Rheometrics Co. RSA-G2), measurement was performed while the temperature was raised from room temperature under the condition of a frequency of 1 Hz, and the storage modulus at 280°C was measured. A sample for measurement (3 mm×40 mm) was cut out from a film having a thickness of about 0.1 to 0.3 mm and measured to determine the storage modulus. The main measurement parameters involved in the measurements are:
Measurement frequency 1Hz
Heating rate 3°C/min Sample measurement length 10mm
Distortion 0.1%

<CTE (linear expansion coefficient)>
CTE is measured using a thermomechanical analyzer (TMA: Thermomechanical Analyzer, manufactured by BRUKER AXS, currently manufactured by Netch Japan) with reference to JPCA Standards "Electronic Circuit Board Standards 3rd Edition" Section 16 Material Standards for Printed Wiring Boards. An average value was obtained during 50°C.

<Production of copolymer>
With reference to the production methods described in JP-A-2009-161743 and JP-A-2010-280771, Rac-dimethylmethylenebis(4,5-benzo-1-indenyl)zirconium dichloride (see the following formula (1) for the structure) as a catalyst, modified methylaluminoxane (manufactured by Tosoh Finechem Co., Ltd., MMAO-3A toluene solution) as a cocatalyst, cyclohexane as a solvent, styrene, divinylbenzene as raw materials, Ethylene was used, optionally 1-hexene. As divinylbenzene, trade name "divinylbenzene (96%)" manufactured by Nippon Steel Chemical & Material (a mixture of meta- and para-isomers containing 96% by mass of divinylbenzene) was used. Polymerization was carried out using a polymerization vessel with a capacity of 10 L, a stirrer and a jacket for heating and cooling.

Synthesis Example P-1
A polymerization vessel was charged with 870 g of toluene, 4530 g of styrene, and 130 g of divinylbenzene (meta-para mixture, manufactured by Nippon Steel Chemical & Materials Co., Ltd., purity: 80%), and nitrogen with a dew point of −50° C. or less was bubbled into the liquid at a liquid temperature of 40° C. while the interior was sufficiently replaced with nitrogen. Further, the gas was switched to ethylene, pressurized to about 0.5 MPa and released to normal pressure, which was repeated 5 times to replace the inside with ethylene gas. Stabilize the internal liquid temperature at 80 ° C., add 50 mmol of modified methylaluminoxane (manufactured by Tosoh Finechem Co., Ltd., MMAO-3A toluene solution) as an aluminum content, introduce ethylene gas and stabilize the pressure at 0.02 MPa (0.2 atm) on the gauge. Polymerization was initiated by adding 30 ml of a toluene solution containing 1 mmol of butylaluminum. During the polymerization, the internal temperature was maintained at 80° C., and ethylene was supplied so as to maintain the internal pressure at 0.02 MPa. After about 3 hours, when a predetermined amount of ethylene was consumed, the ethylene gas was released, and a small amount of isopropanol was added to the polymerization solution to terminate the polymerization. After that, a sufficiently large amount of methanol was added to the resulting polymerization liquid to recover the copolymer. This copolymer was air-dried and further vacuum-dried at 30° C. for one day to obtain about 930 g of copolymer P-1. Table 1 shows the composition and number average molecular weight of the copolymer.

formula (1)

Synthesis Example P-2
Polymerization was carried out in the same manner as in P-1, except that the internal pressure of the polymerization vessel was maintained at 0.00 MPa (0.0 atm in gauge) and the internal temperature during polymerization was maintained at 100°C. About 600 g of copolymer P-2 was obtained. Table 1 shows the composition and number average molecular weight of the copolymer.

Synthesis Example P-3
With reference to the production methods described in JP-A-9-309925, JP-A-2009-161743, and JP-A-2010-280771, polymerization was carried out in the same manner using Rac-dimethylmethylenebis(4,5-benzo-1-indenyl)zirconium dichloride (see formula (1) above for the structure) as a catalyst. Table 1 shows the composition and number average molecular weight of copolymer P-3.

Synthesis Example P-4
With reference to the production methods described in JP-A-9-40709, JP-A-9-309925, JP-A-2009-161743, and JP-A-2010-280771, polymerization was carried out in the same manner using dimethylmethylenebiscyclopentadienylzirconium dichloride (see formula (2) below for the structure) as a catalyst. Table 1 shows the composition and number average molecular weight of copolymer P-4.

formula (2)

The solubility of the obtained copolymers P-1 to P-4 in methyl ethyl ketone was examined as follows. At 25° C., 3 g of fine particles of the copolymer were accurately weighed in a container equipped with a stirrer placed on an electronic balance, 3 g of methyl ethyl ketone was added, and the mixture was stirred for 15 minutes. If undissolved, the same operation was performed while adding methyl ethyl ketone in increments of 3 g, and the mass of methyl ethyl ketone until it was completely dissolved was measured and the solubility was used. If the solubility at 25° C. is 40 g or more in terms of 100 g of methyl ethyl ketone, it is described as excellent; if it is 20 g or more and less than 40 g, it is fair;

Other raw materials are as follows.
A bifunctional polyphenylene ether oligomer (OPE-2St, modified polyphenylene ether having vinylbenzyl groups at both ends, number average molecular weight of 1200) was obtained by diluting a toluene solution product manufactured by Mitsubishi Gas Chemical Co., Ltd. with toluene, adding a large amount of methanol to precipitate methanol, air-drying, and drying under reduced pressure to obtain a powdery polyphenylene ether oligomer and use it.

1,2-polybutadiene (PBd): liquid polybutadiene, Nippon Soda Co., Ltd. "B-3000", number average molecular weight 3200, viscosity 210 Poise (45 ° C.)

SEBS: Hydrogenated styrene thermoplastic elastomer, "Tuftec H1041" manufactured by Asahi Kasei Corporation, number average molecular weight 58000

Perbutyl P (α,α'-di(t-butylperoxy)diisopropylbenzene) manufactured by NOF Corporation was used as a curing agent.

Example 1
P-1 (ethylene-styrene-divinylbenzene copolymer) obtained in Synthesis Example and a solvent (toluene) were heated to about 60° C. and stirred to dissolve the copolymer using a vessel equipped with a heating/cooling jacket and a stirring blade. Furthermore, 1 part by mass of a curing agent was added to 100 parts by mass of the resin component excluding the curing agent and the solvent, and the mixture was dissolved and stirred to obtain a varnish-like composition. The obtained composition was poured into a Teflon (registered trademark) formwork (frame part length 7 cm, width 7 cm, thickness 0.2 mm, 0.5 mm, or 1.0 mm) on a PET sheet placed on a glass plate, air-dried, and further dried at 60 ° C. for 3 hours or more in a vacuum dryer to obtain an uncured sheet. Further, a Teflon sheet and a Teflon mold were placed under a load of 5 MPa in a press, and heat treated at 120° C. for 30 minutes, 150° C. for 30 minutes, and then at 200° C. for 120 minutes.

Examples 2-6
A curable resin composition was prepared according to the formulation shown in Table 2 (the units in the table are parts by mass) in the same manner as in Example 1, and uncured sheets and cured sheets of the compositions of Examples were obtained in the same manner.

Comparative Examples 1-3
A curable resin composition was prepared according to the formulation shown in Table 2 (units are parts by mass) in the same manner as in Example 1, and an uncured sheet and a cured sheet of the composition of Comparative Example were obtained in the same manner.

Table 2 shows the gel content, tensile modulus at 25° C., storage modulus at 280° C., dielectric constant, dielectric loss tangent, coefficient of linear expansion (CTE), and water absorption of the cured sheets obtained in Examples and Comparative Examples.

Table 2 also shows the results of visually confirming whether the state of the varnish is good (Good) or not (NG).

By comparing the cured products of the P-1 and P-2 resins alone (Examples 1 and 2) and the cured products of the P-3 and P-4 resins alone (Comparative Examples 1 and 2), it can be seen that the cured products of the copolymers of the present invention exhibit a high tensile modulus (25° C., that is, room temperature) that satisfies the conditions of the present invention. Furthermore, the cured product of the composition of OPE-2St and P-1 (Example 5) that gives a hard, independently cured product, the cured product of the composition of P-4 and P-1 that gives a soft, independently cured product (Example 3), and the cured product of the composition of 1,2-polybutadiene, SEBS, and P-1 (Example 4) also exhibit high tensile moduli. A cured body of the composition of the present invention can easily exhibit a high tensile modulus of 100 MPa or more at room temperature. Furthermore, it was confirmed that cured sheets made of the copolymer of the present invention and the composition containing the copolymer of the present invention exhibit low dielectric constant and dielectric loss tangent.

As a further test, the tackiness of the uncured sheets obtained in each of Examples and Comparative Examples was evaluated by feeling with hands. First, the uncured sheets of Examples 1, 2, and 5 were hard and had no tackiness (self-adhesiveness). The uncured sheets of Examples 3, 4, and 6 were somewhat tacky, but could be handled as free-standing sheets. The tackiness of the uncured sheets of Comparative Examples 1, 2, and 3 was higher than that of the uncured sheets of each of the other Examples (especially Examples 3 and 6). In particular, the uncured sheets of Comparative Examples 2 and 3 had remarkably high tackiness, and it was difficult to peel off the sheets of each Comparative Example when they were brought into close contact with each other. From this result, it was confirmed that the uncured sheet made of the copolymer of the present invention and the composition containing the copolymer of the present invention can relatively reduce tackiness.

Claims

An aromatic vinyl compound-aromatic polyene copolymer that satisfies all of the following conditions (1) to (4).
(1) The copolymer has a number average molecular weight of 500 or more and less than 100,000.
(2) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and the content of the aromatic vinyl compound monomer units exceeds 70% by mass.
(3) The aromatic polyene is one or more selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and/or vinylene groups in the molecule, and the content of vinyl groups and/or vinylene groups derived from the aromatic polyene units is 2 or more and less than 30 per number average molecular weight.
(4) One or more selected from olefin monomer units having 2 to 20 carbon atoms may be included, and the sum of the aromatic vinyl compound monomer units and the aromatic polyene monomer units and, if present, the olefin monomer units is 100% by mass.
The aromatic vinyl compound-aromatic polyene copolymer according to claim 1, wherein the content of the olefin monomer unit is 0% by mass or more and less than 30% by mass with respect to the total 100% by mass of the aromatic vinyl compound monomer unit, the aromatic polyene monomer unit, and the olefin monomer unit when present.
3. The aromatic vinyl compound-aromatic polyene copolymer according to claim 2, which does not contain olefin monomer units.
A composition comprising the aromatic vinyl compound-aromatic polyene copolymer according to any one of claims 1 to 3 and one or more selected from the following (a) to (d).
(a) a curing agent (b) one or more resins selected from hydrocarbon elastomers, polyphenylene ether resins and aromatic polyene resins (c) monomers (d) another olefin-aromatic vinyl compound-aromatic polyene copolymer (i) that satisfies all of the following conditions (i) to (iv): the copolymer has a number average molecular weight of 500 or more and less than 100,000.
(ii) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and the content of aromatic vinyl compound monomer units is 70% by mass or less.
(iii) The aromatic polyene is one or more selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and/or vinylene groups in the molecule, and the content of vinyl groups and/or vinylene groups derived from the aromatic polyene units is 1.5 or more and less than 20 per number average molecular weight.
(iv) The olefin is one or more selected from olefins having 2 to 20 carbon atoms, the content of olefin monomer units is 30% by mass or more, and the total of the olefin monomer units, aromatic vinyl compound monomer units and aromatic polyene monomer units is 100% by mass.
A varnish comprising the copolymer according to any one of claims 1 to 3 or the composition according to claim 4 and (h) a solvent.
6. A varnish according to claim 5, wherein the solvent is MEK (methyl ethyl ketone).
A cured product of the aromatic vinyl compound-aromatic polyene copolymer according to any one of claims 1 to 3.
A cured product of the composition according to claim 4 .
A cured body of the varnish according to claim 5 or 6.
The cured body according to any one of claims 7 to 9, which is an electrical insulating material.
A CCL substrate, FCCL substrate, interlayer insulating material, bonding sheet, or coverlay, comprising the cured body according to any one of claims 7 to 9.